Process and material properties of HfLaO(x) prepared by atomic layer deposition

Abstract

The atomic layer deposition (ALD) process of hafnium-lanthanum oxide (HfLaO(x)) using La(iPrCp)(3) and Hf(NEtMe)(4) precursors is described. It has been found that when Hf precursor is introduced, the ALD process of La(2)O(3) is significantly improved in terms of its deposition rate and self-limiting property. An enhanced deposition rate and good controllability of the composition ratio of HfLaO(x) was achieved. The mechanism behind this enhancement is discussed. Using high-resolution X-ray photoelectron spectroscopy, the band structure of HfLaO(x) as a function of La percentage is analyzed. It has been found that the energy bandgap (E(g)) and conduction and valance band offsets (Delta E(c) and Delta E(v)) of HfLaO(x) change linearly with the La percentage. The E(g) changes from 4.92 to 5.67 eV and the Delta E(c) from 1.21 to 2.4 eV as the La percentage varies from 0 to 81%. The ALD HfLaO(x) dielectric exhibits excellent electrical properties with a low leakage current and a high breakdown field, even after high-temperature anneal up to 1050 degrees C, which makes HfLaO(x) a promising candidate for complementary metal oxide semiconductor integrated-circuit application. (C) 2008 The Electrochemical Society.